Pharmacogenetics — the use of genetic information to guide medication prescribing decisions — is a foundation of precision medicine, with growing implications for safety, efficacy, and cost savings. At the UCSF School of Pharmacy, Akinyemi Oni-Orisan, PharmD, PhD, associate professor in the Department of Clinical Pharmacy, conducts studies to help ensure that pharmacogenetics will benefit broad patient groups equitably.

We spoke with Oni-Orisan about: 

• progress in the field of pharmacogenetics
• remaining barriers to implementation
• the critical role pharmacists play in ensuring access to this tool for all patients

Why is pharmacogenetics so important to patient care today?

About 7 billion prescriptions are filled every year in the United States. This has contributed to the treatment of numerous conditions and increased life expectancy. But this also means there’s an increased possibility of adverse drug reactions, some of which can lead to hospitalization or death. Pharmacogenetics is important because there is strong evidence proving its effectiveness in preventing adverse drug reactions.

How far has pharmacogenetics progressed from research into routine clinical practice?

There’s been really exciting progress in the past decade.

There have been many health systems that have adopted the implementation of pharmacogenetics in routine care, including UCSF, which is the first program in California to do preemptive pharmacogenetic testing.

Preemptive pharmacogenetic testing is when test results are kept in the patient’s electronic health record and can be used to guide new therapies at future health visits. The establishment of this program at UCSF was spearheaded by Bani Tamraz, PharmD, PhD, associate professor in the Department of Clinical Pharmacy.

Another piece of progress is expanded health coverage for pharmacogenetics. In California, pharmacogenetic testing is covered for millions of low-income residents.

You recently led a paper examining barriers to pharmacogenetics implementation in the United States. What challenges remain most significant?

In our paper, Progress in Pharmacogenomics Implementation in the United States: Barrier Erosion and Remaining Challenges, we examined the challenges and solutions, covering the full spectrum of pharmacogenetics translation from evidence generation to implementation. One of the barriers we homed in on is the lack of inclusion of study participants from diverse backgrounds in pharmacogenetics research.

Inclusion is a central theme in your work. Why does it matter so much in pharmacogenetics?

If you’re lucky enough to more closely match the “average” study participant, you are more likely to benefit from precision medicine. But if you’re on the outside of the data you might derive less benefit or even be harmed by such as an adverse drug reaction. This is one of my primary areas of interest as a researcher and as a clinical scientist. We’re still not at the point in pharmacogenetics where everyone benefits equitably. We need to make sure that we include as many genetic and non-genetic characteristics as possible in our research.

You recently authored a Clinical Pharmacology & Therapeutics Perspective that describes how findings from a research study you conducted led to a national update to the Clinical Pharmacogenetics Implementation Consortium (CPIC) prescribing guidance. What changed, and why does that matter for inclusion in pharmacogenetics?

I can generate as much evidence as possible, but if it’s not going to translate to the patient, then it’s pointless. That’s where CPIC comes in. CPIC is a working group of experts that reviews the literature and makes clinical recommendations for specific gene–drug pairs, including whether a dose should be changed or a different drug should be used based on someone’s genetic code.

They’ve generated dozens of guidelines, but producing those guidelines takes time, even though new evidence emerges frequently. To help address that, CPIC maintains online tables that can be updated more rapidly, but even then, someone has to identify the evidence and bring it forward.

In our study, we identified genetic variants — common in people with sub-Saharan African ancestry — that strongly affect the risk of an adverse drug reaction to statins. These are widely used, low-cost cholesterol-lowering drugs.
We felt our evidence was strong enough that it shouldn’t wait years to be incorporated, so we reached out directly to CPIC. Within a couple of months, they convened an expert panel, reviewed the data, and updated their tables to reflect the new evidence.

That experience led us to publish the perspective you mentioned. One of the main points of this perspective was to encourage other researchers to also reach out to CPIC. If you have strong evidence that can improve patient care, especially for populations that have historically been left out, sometimes you have to be proactive to make sure that evidence gets translated into practice.

Looking ahead, what role can pharmacists play in making pharmacogenetics more equitable and accessible?

As I mentioned earlier, UCSF was the first in California to implement preemptive pharmacogenetics. I imagine that, in the coming years, other large health systems and academic medical centers will adopt this.

One of the frontiers moving forward is to get pharmacogenetics into those areas —rural areas, Black and brown communities — where people don’t have access to large health systems like UCSF.

Pharmacists are often the most accessible health care providers — no appointments needed, no co-pay required. Imagine if patients had a PDF of their pharmacogenetic test results that they could take to a pharmacy. The pharmacist could look at the results and call the physician and say, “We need to change the medication because of this pharmacogenetic information.” The PDF could be kept and used for the rest of the person’s life.

What is one of the major misconceptions around precision medicine and pharmacogenetics?

One of the misconceptions is that pharmacogenetics is only for new, expensive, uncommon medications such as the cutting-edge cancer therapies available. On the contrary, patients may be surprised to learn that many of their $5-a-month prescriptions can be better optimized by pharmacogenetics, and that this optimization can make a big difference. We could prevent hundreds of thousands of hospitalizations every year if we knew more patients’ pharmacogenetic information.